I don't think there is any good or bad guys. Just human reaction to an improbable situation to properly psychoanalysis. Everyone has murder basically someone in this show. The only delusion that's really concrete is David's need to be loved that it makes him blind to who Syd really is... Syd is a extremely flawed person, and she honestly never done anything less than being a delusional narcissist in pivotal points of the narrative. She constantly tries to bend David's mind to believe in the way she see. She sees herself as a God, because of her powers and etc. She poorly justify her action while condemning David. David had to grow through a lifetime of shyt to it finally broke him. Yet, he still fought through 99% of it. When his sister was murder... It was the final straw. Where was Syd to comfort for him or go the extra mile like David when she was trapped in the Maze? Hell, fukking Lenny gave a shyt more unconditionally about David than Syd ever did. If you let yourself get that easily manipulated by the SK and pretending you have some sort of moral code/greater good all of a sudden after YOU let the Shadow King free in the first place in Season 1. Constantly told Melanie that you valued David over everyone else. Syd is full of shyt. She only serves herself and she got manipulated by SK.I just caught up and finished the season when the puzzle pieces started coming together.
This "good" guy version of Dvid was just a delusion to win over Syd. Still feel it's kinda fukked to judge David for shyt he hasn't done which of course may potentially cause the very future they're trying to avoid. He may not even be evil now that he knows of his potential future he may just do whatever he feels is right now without Division 3. Season 3: Legion and Lenny fukkery and Division 3 working with Shadow King has a lot of potential.
Also, the idea that David destroys the world was only exacerbated by moral panic started by SK and Syd. Now, SK has Division 3 under his control.I honestly believe this was an elaborate plan devised by the shadow king and that Future Syd was never real. David wanted to leave and live a simple life prior to his trial.